This invention relates to a process for outgassing liquid-crystalline materials by a thermal treatment under reduced pressure.
Liquid-crystalline materials are widely used industrially in the manufacture of opto-electronic components. In such display systems, the liquid-crystalline material is present in 5-30 .mu.m thick layers between two transparent electrodes.
Liquid-crystalline materials which frequently can consist not of only one component but can represent a mixture of up to more than 20 individual components, are viscous liquids which are capable of dissolving considerable amounts of inert gas. These dissolved gas fractions can escape again from the liquid-crystalline material, during or after the step of filling the display elements, with destruction of optical homogeneity, and can lead to the formation of bubbles, whereby the particular display element becomes useless. Particularly when large-area display elements are filled, this entails high reject rates in the production sequence.
The conventional process for outgassing liquids by applying a reduced pressure turns out to be very protracted and incomplete due to the viscous nature of the material which is to be outgassed.
There is therefore a demand for a process for an effective and complete outgassing of liquid-crystalline materials.